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All Journal Jurnal Fisika Unand Buana Information Technology and Computer Sciences (BIT and CS) Jurnal Lentera - Penelitian dan Pengabdian Masyarakat
Afrioni Roma Rio
Sam Ratulangi University
Agriculture, Biological Sciences & Forestry Computer Science & IT Earth & Planetary Sciences Electrical & Electronics Engineering Energy Environmental Science Materials Science & Nanotechnology Medicine & Pharmacology Physics Public Health Social Sciences

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Agglomerative Clustering of 2022 Earthquakes in North Sulawesi, Indonesia Afrioni Roma Rio; Berton Maruli Siahaan
Buana Information Technology and Computer Sciences (BIT and CS) Vol 4 No 2 (2023): Buana Information Technology and Computer Sciences (BIT and CS)
Publisher : Information System; Universitas Buana Perjuangan Karawang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36805/bit-cs.v4i2.5361

Abstract

This paper presents a cluster analysis of earthquake data in the surrounding region of North Sulawesi, Indonesia. The dataset comprises seismic data recorded throughout the year 2022, obtained from the BMKG earthquake repository. A total of 211 earthquakes were included in the analysis, with a minimum magnitude threshold of 2.5 and a maximum depth of 300 km. The agglomerative clustering technique, combined with the elbow method, was employed to determine the optimal and distinct number of clusters. As a result, four unique clusters were identified. Cluster 1 exhibited high magnitudes, with an average magnitude of 4.4, and shallow depths, averaging at 20 km. Cluster 2 also had high magnitudes, averaging at 4.4, but deeper depths, with an average of 199 km. Cluster 3 consisted of earthquakes with low magnitudes, averaging at 3.4, and shallow depths, averaging at 21 km. Lastly, Cluster 4 comprised earthquakes with low magnitudes, averaging at 3.4, but deeper depths, with an average of 136 km. Among the 211 earthquakes, 29 were assigned to Cluster 1, 39 to Cluster 2, 100 to Cluster 3, which had the highest population, and 43 to Cluster 4. This study provides valuable insights into the clustering patterns and characteristics of earthquakes in the region, contributing to a better understanding of seismic activity in North Sulawesi, Indonesia
Strain-Induced Control of Magnetic Anisotropy Energy in NbS2 Monolayer: First-Principles Study Berton Maruli Siahaan; Afrioni Roma Rio
Jurnal Fisika Unand Vol 12, No 4 (2023)
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jfu.12.4.667-674.2023

Abstract

In this work, we investigate the strain controllability of magnetic anisotropy energy (MAE) in the monolayer form of niobium disulfide (NbS2) using density functional theory (DFT). Our calculation reveals a negative MAE of -1.82 meV, indicating a preference for spins to align in the in-plane directions (x or y). By systematically applying biaxial tensile strain to the NbS2 monolayer, ranging from 1% to 10%, we observe a linear relationship between strain and MAE. Interestingly, the strain-induced modulation of MAE leads to a remarkable phenomenon, where the easy axis of magnetization shifts from the in-plane to an out-of-plane orientation at a critical strain of 7%. This ability to switch the magnetic anisotropy by manipulating strain demonstrates the promising potential of NbS2 monolayer in the development of spintronic devices.
Penentuan Nilai Koefisien Restitusi Kelereng Kaca menggunakan Metode Pencitraan Jeda Waktu Sederhana Mahendra Kusuma Nugraha; Ernawatil Gani; Afrioni Roma Rio; Berton M. Siahaan
Jurnal Lentera - Penelitian dan Pengabdian Masyarakat Vol 4 No 1 (2023): Jurnal Lentera - Penelitian dan Pengabdian Masyarakat
Publisher : Yayasan Bina Lentera Insan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.57207/lentera.v4i1.47

Abstract

Pencitraan jeda waktu (time-lapse imaging) telah dilakukan untuk mengamati fenomena fisis tumbukan lenting tidak sempurna antara kelereng kaca dengan permukaan lantai ubin. Kelereng kaca dijatuhkan pada ketinggian tertentu hingga menumbuk permukaan lantai dan mengalami pemantulan berulang. Kejadian tersebut direkam menggunakan kamera perangkat ponsel pintar Infinix® Hot S3 dengan kecepatan kerangka per detik adalah 30 kerangka. Analisis fotografi jeda waktu kemudian dilakukan dengan metode pemisahan kerangka (frame splitting) yang kemudian diamati secara visual untuk menentukan ketinggian setiap pantulan yang terjadi. Hasil analisis dan pengukuran tinggi maksimum untuk keadaan awal, keadaan pantulan pertama dan keadaan pantulan kedua masing-masing: 15.7 cm, 13,65 cm dan 11,45 cm. Angka koefisien restitusi kelereng kaca—berdasarkan data yang diperoleh—pada ketinggian maksimum mula-mula (????0) menuju pantulan pertama (????1) adalah sebesar ± 0,93242 dan pantulan pertama (????1) menuju pantulan kedua (????2) adalah sebesar. ± 0,91587. Perolehan tersebut membuktikan bahwa interaksi yang terjadi adalah interaksi tumbukan lenting tak sempurna dikarenakan ????≠1.
Co-Authors Berton M. Siahaan Berton Maruli Siahaan Ernawatil Gani Salsabila, Unik Hanifah